Topic summary
Gerrymander

Extracted from the Wikipedia article Gerrymandering.
Incumbent gerrymandering
Gerrymandering can also be done to help incumbents as a whole, effectively making every district a packed one and greatly reducing the potential for competitive elections. This is particularly likely to occur when the minority party has significant obstruction power: unable to enact a partisan gerrymander, the legislature instead agrees to ensure its own reelection.